Multi-gradient raised frame in bulk acoustic wave device

ABSTRACT

Aspects of this disclosure relate to a bulk acoustic wave device with a multi-gradient raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-gradient raised frame structure. The multi-gradient raised frame structure includes a first raised frame layer and a second raised frame layer. The second raised frame layer extends beyond the first raised frame layer. The second raised frame layer is tapered on opposing sides.

CROSS REFERENCE TO PRIORITY APPLICATION

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 C.F.R. § 1.57.This application claims the benefit of priority of U.S. ProvisionalApplication No. 63/080,530, filed Sep. 18, 2020 and titled “BULKACOUSTIC WAVE DEVICE WITH RAISED FRAME STRUCTURE,” the disclosure ofwhich is hereby incorporated by reference in its entirety.

BACKGROUND Technical Field

Embodiments of this disclosure relate to acoustic wave devices and, morespecifically, to bulk acoustic wave devices.

Description of Related Technology

Acoustic wave filters can be implemented in radio frequency electronicsystems. For instance, filters in a radio frequency front end of amobile phone can include one or more acoustic wave filters. A pluralityof acoustic wave filters can be arranged as a multiplexer. For instance,two acoustic wave filters can be arranged as a duplexer.

An acoustic wave filter can include a plurality of acoustic resonatorsarranged to filter a radio frequency signal. Example acoustic wavefilters include surface acoustic wave (SAW) filters and bulk acousticwave (BAW) filters. BAW filters include BAW resonators. Example BAWresonators include film bulk acoustic wave resonators (FBARs) andsolidly mounted resonators (SMRs). In BAW resonators, acoustic wavespropagate in a bulk of a piezoelectric layer.

For BAW devices, achieving a high quality factor (Q) is generallydesirable. However, Q can vary in BAW devices due to variations inmanufacturing and/or for other reasons.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is a bulk acoustic wave device with amulti-gradient raised frame. The bulk acoustic wave device includes afirst electrode, a second electrode, a piezoelectric layer positionedbetween the first electrode and the second electrode, and amulti-gradient raised frame structure configured to cause lateral energyleakage from a main acoustically active region of the bulk acoustic wavedevice to be reduced. The multi-gradient raised frame structure istapered on opposing sides. The bulk acoustic wave device is configuredto generate a bulk acoustic wave.

The multi-gradient raised frame structure can surround the mainacoustically active region of the bulk acoustic wave device in planview. The multi-gradient raised frame structure can have a non-gradientportion between two gradient portions. The multi-gradient raised framestructure can consist essentially of gradient portions.

The multi-gradient raised frame structure can include a plurality ofraised frame layers. The plurality of raised frame layers can include afirst raised frame layer and a second raised frame layer. The secondraised frame layer can extend beyond the first raised frame layer on theopposing sides. The first raised frame layer can have a lower acousticimpedance than the piezoelectric layer and/or the second raised framelayer. The first raised frame layer can be an oxide layer, and thesecond raised frame layer can be metallic. The first raised frame layercan be a silicon dioxide layer, and the second raised frame layer can bemetallic. The first raised frame layer can be positioned between thefirst and second electrodes. The second electrode can be positionedbetween the first and second raised frame layers in some instances. Thesecond raised frame layer can have a first taper angle on a first sideand a second taper angle on a second side, in which and the first andsecond taper angles are in a range from 5 degrees to 45 degrees.

The multi-gradient raised frame structure can be a convex structurerelative to the piezoelectric layer.

The bulk acoustic wave device can be a film bulk acoustic resonator.

Another aspect of this disclosure is an acoustic wave filter with amulti-gradient raised frame bulk acoustic wave device. The acoustic wavefilter includes a bulk acoustic wave device and at least one additionalacoustic wave device that are together arranged to filter a radiofrequency signal. The bulk acoustic wave device includes a firstelectrode, a second electrode, a piezoelectric layer positioned betweenthe first electrode and the second electrode, and a multi-gradientraised frame structure configured to cause lateral energy leakage from amain acoustically active region of the bulk acoustic wave device to bereduced. The multi-gradient raised frame structure is tapered onopposing sides.

The least one additional acoustic wave device can include a second bulkacoustic wave device that includes a second multi-gradient raised framestructure that is tapered on opposing sides.

The multi-gradient raised frame structure can include a first raisedframe layer and a second raised frame layer. The first raised framelayer can include an oxide, and the second raised frame layer can bemetallic. The second raised frame layer can extend beyond the firstraised frame layer on the opposing sides.

Another aspect of this disclosure is a wireless communication devicethat includes an acoustic wave filter and an antenna operatively coupledto the acoustic wave filter. The acoustic wave filter includes a bulkacoustic wave device. The bulk acoustic wave device includes a firstelectrode, a second electrode, a piezoelectric layer positioned betweenthe first electrode and the second electrode, and a multi-gradientraised frame structure configured to cause lateral energy leakage from amain acoustically active region of the bulk acoustic wave device to bereduced. The multi-gradient raised frame structure is tapered onopposing sides.

The wireless communication device can be a mobile phone. The acousticwave filter can be included in a multiplexer.

Another aspect of this disclosure is a bulk acoustic wave device with amulti-gradient raised frame. The bulk acoustic wave device includes afirst electrode, a second electrode, a piezoelectric layer positionedbetween the first electrode and the second electrode, and amulti-gradient raised frame structure. The multi-gradient raised framestructure includes a first raised frame layer and a second raised framelayer. The second raised frame layer extends beyond the first raisedframe layer. The second raised frame layer is tapered on opposing sides.The bulk acoustic wave device is configured to generate a bulk acousticwave.

The second raised frame layer can extend beyond the first raised framelayer on the opposing sides, where the opposing sides include a firstside toward a main acoustically active region of the bulk acoustic wavedevice and a second side away from the main acoustically active region.

The first raised frame layer can have a lower acoustic impedance thanthe piezoelectric layer. The first raised frame layer can include anoxide, and the second raised frame layer can include a metal. The secondraised frame layer can include one or more of ruthenium, molybdenum,tungsten, platinum, or iridium.

The first raised frame layer can include a metal. The first raised framelayer can include a polymer.

The multi-gradient raised frame structure can have a non-gradientportion between two gradient portions. The multi-gradient raised framestructure can consist essentially of gradient portions.

The first raised frame layer can be positioned between the firstelectrode and the second electrode.

The second electrode can be positioned between the second raised framelayer and the first raised frame layer. The first raised frame layer canalso be positioned between the piezoelectric layer and the secondelectrode.

The second raised frame layer can have a first taper angle on a firstside and a second taper angle on a second side, and the first and secondtaper angles can each be greater than 5 degrees and less than 45degrees.

The second raised frame layer can be a convex structure relative to asurface of the piezoelectric layer.

The multi-gradient raised frame structure can surround a mainacoustically active region of the bulk acoustic wave device in planview.

The bulk acoustic wave device can be a film bulk acoustic resonator.

Another aspect of this disclosure is an acoustic wave filter thatincludes a bulk acoustic wave device and at least one additionalacoustic wave device together arranged to filter a radio frequencysignal. The bulk acoustic wave device includes a first electrode, asecond electrode, a piezoelectric layer positioned between the firstelectrode and the second electrode, and a multi-gradient raised framestructure including a first raised frame layer and a second raised framelayer. The second raised frame layer extends beyond the first raisedframe layer. The second raised frame layer is tapered on opposing sides.

The at least one additional acoustic wave device can include a secondbulk acoustic wave device that includes a second multi-gradient raisedframe structure that is tapered on opposing sides.

Another aspect of this disclosure is a packaged radio frequency modulethat includes an acoustic wave filter configured to filter a radiofrequency signal, a radio frequency circuit element, and a packagestructure enclosing the acoustic wave filter and the radio frequencycircuit element. The acoustic wave filter includes a bulk acoustic wavedevice. The bulk acoustic wave device includes a first electrode, asecond electrode, a piezoelectric layer positioned between the firstelectrode and the second electrode, and a multi-gradient raised framestructure including a first raised frame layer and a second raised framelayer. The second raised frame layer extends beyond the first raisedframe layer. The second raised frame layer is tapered on opposing sides.

The radio frequency circuit element can be a radio frequency switch. Theradio frequency circuit element can be a radio frequency amplifier.

Another aspect of this disclosure is a bulk acoustic wave device thatincludes a first electrode, a second electrode, a piezoelectric layerpositioned between the first electrode and the second electrode, and amulti-layer raised frame structure configured to cause lateral energyleakage from a main acoustically active region of the bulk acoustic wavedevice to be reduced. The multi-layer raised frame structure includes afirst raised frame layer embedded in the piezoelectric layer and asecond raised frame layer. The first raised frame layer has a loweracoustic impedance than the piezoelectric layer. The second raised framelayer at least partly overlaps with the first raised frame layer in araised frame region of the bulk acoustic wave device. The bulk acousticwave device is configured to generate a bulk acoustic wave.

The second raised frame layer can be embedded in the piezoelectriclayer.

The first raised frame layer can include an oxide, and the second raisedframe layer can include a metal. The first raised frame layer can be asilicon dioxide layer, and the second raised frame layer can bemetallic. The second raised frame layer can be embedded in thepiezoelectric layer.

The multi-layer raised frame structure can be a multi-gradient raisedframe structure. The second raised frame layer can extend beyond thefirst raised frame layer on opposing sides of the multi-layer raisedframe structure. The multi-gradient raised frame structure can have anon-gradient portion between two gradient portions. The second raisedframe layer can have a first taper angle on a first side and a secondtaper angle on a second side, and the first and second taper angles caneach be greater than 5 degrees and less than 45 degrees.

The multi-layer raised frame structure can surround the mainacoustically active region of the bulk acoustic wave device in planview.

The bulk acoustic wave device can be a film bulk acoustic resonator.

Another aspect of this disclosure is an acoustic wave filter comprisingthat includes a bulk acoustic wave device and the at least oneadditional acoustic wave device together arranged to filter a radiofrequency signal. The bulk acoustic wave device includes a firstelectrode, a second electrode, a piezoelectric layer positioned betweenthe first electrode and the second electrode, and a multi-layer raisedframe structure including a first raised frame layer and a second raisedframe layer. The first raised frame layer is embedded in thepiezoelectric layer and has a lower acoustic impedance than thepiezoelectric layer. The second raised frame layer at least partlyoverlaps with the first raised frame layer.

The at least one additional acoustic wave device can include a secondbulk acoustic wave device that includes a raised frame layer embedded ina piezoelectric layer of the second bulk acoustic wave device.

The multi-layer raised frame structure can be a multi-gradient raisedframe structure. The second raised frame layer can have a first taperangle on a first side and a second taper angle on a second side, and thefirst and second taper angles can each be greater than 5 degrees andless than 45 degrees. The first raised frame layer can be an oxide, andthe second raised frame layer can be metallic. The first raised framelayer can be a silicon dioxide layer.

Another aspect of this disclosure is a packaged radio frequency modulethat includes an acoustic wave filter, a radio frequency circuitelement, and a package structure enclosing the acoustic wave filter andthe radio frequency circuit element. The acoustic wave filter includes abulk acoustic wave device. The bulk acoustic wave device includes afirst electrode, a second electrode, a piezoelectric layer positionedbetween the first electrode and the second electrode, and a multi-layerraised frame structure including a first raised frame layer and a secondraised frame layer. The first raised frame layer is embedded in thepiezoelectric layer and has a lower acoustic impedance than thepiezoelectric layer. The second raised frame layer at least partlyoverlaps with the first raised frame layer.

The radio frequency circuit element can be a radio frequency switch. Theradio frequency circuit element can be a radio frequency amplifier.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the innovations have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment. Thus, theinnovations may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

The present disclosure relates to U.S. patent application Ser. No.______ [Attorney Docket SKYWRKS.1132A1], titled “BULK ACOUSTIC WAVEDEVICE WITH MULTI-GRADIENT RAISED FRAME,” filed on even date herewith,the entire disclosure of which is hereby incorporated by referenceherein. The present disclosure also relates to U.S. patent applicationSer. No. ______ [Attorney Docket SKYWRKS.1132A3], titled “BULK ACOUSTICWAVE DEVICE WITH RAISED FRAME STRUCTURE,” filed on even date herewith,the entire disclosure of which is hereby incorporated by referenceherein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view of a bulk acoustic wave (BAW)device with a dual gradient raised frame structure according to anembodiment.

FIG. 2A is a plan view of an example BAW device with a frame regionsurrounding a main acoustically active region. FIG. 2B is a plan view ofanother BAW device with a frame region surrounding a main acousticallyactive region.

FIG. 3A is a cross sectional view of a BAW device with a dual gradientraised frame structure. FIG. 3B shows simulation results for the BAWdevice of FIG. 3A.

FIG. 4A is a cross sectional view of a portion of a BAW device with asingle gradient raised frame structure. FIG. 4B shows simulation resultsfor the BAW device of FIG. 4A.

FIG. 5A is a cross sectional view of a BAW device with a dual gradientraised frame structure. FIG. 5B shows simulation results for the BAWdevice of FIG. 5A.

FIG. 6 is a cross sectional view of a solidly mounted resonator (SMR)BAW device with a dual gradient raised frame structure according to anembodiment.

FIG. 7 is a cross-sectional view of a BAW device with a multi-gradientraised frame structure according to an embodiment.

FIG. 8 is a cross-sectional view of a BAW device according to anotherembodiment.

FIG. 9 is a cross-sectional view of a BAW device according to anotherembodiment.

FIG. 10 is a cross-sectional view of a BAW device with a single raisedframe layer according to an embodiment.

FIG. 11 is a cross-sectional view of a BAW device with a single raisedframe layer according to another embodiment.

FIG. 12 is a cross-sectional view of a BAW device according to anotherembodiment.

FIG. 13 is a cross-sectional view of a BAW device with a multi-gradientraised frame structure between a piezoelectric layer and a lowerelectrode according to an embodiment.

FIG. 14 is a cross-sectional view of a BAW device with a multi-gradientraised frame structure having raised frame layers on opposing sides of apiezoelectric layer according to an embodiment.

FIG. 15 is a cross-sectional view of a BAW device with a multi-layerraised frame structure having raised frame layers on opposing sides of apiezoelectric layer according to an embodiment.

FIG. 16 is a cross-sectional view of a BAW device with a multi-layerraised frame structure having a raised frame layer embedded in apiezoelectric layer according to an embodiment.

FIG. 17 is a schematic cross-sectional view of a BAW device with amulti-layer raised frame structure with gradients according to anembodiment.

FIG. 18 is a schematic cross-sectional view of a BAW device with a dualgradient raised frame structure with a raised frame layer embedded inthe piezoelectric layer according to an embodiment.

FIG. 19 is a schematic cross-sectional view of a BAW device with a dualgradient raised frame structure according to an embodiment.

FIG. 20 illustrates a schematic cross-sectional view of a BAW deviceaccording to an embodiment.

FIG. 21 illustrates a schematic cross-sectional view of a BAW deviceaccording to another embodiment.

FIG. 22 illustrates a taper angle for a gradient portion of a raisedframe layer.

FIG. 23 illustrates examples gradient portions of a raised frame layerwhere the gradient portion are non-linear.

FIG. 24 is a schematic diagram of a ladder filter that includes a bulkacoustic wave resonator according to an embodiment.

FIG. 25 is a schematic diagram of a lattice filter that includes a bulkacoustic wave resonator according to an embodiment.

FIG. 26 is a schematic diagram of a hybrid ladder lattice filter thatincludes a bulk acoustic wave resonator according to an embodiment.

FIG. 27A is schematic diagram of an acoustic wave filter. FIG. 27B is aschematic diagram of a duplexer that includes an acoustic wave filteraccording to an embodiment. FIG. 27C is a schematic diagram of amultiplexer that includes an acoustic wave filter according to anembodiment. FIG. 27D is a schematic diagram of a multiplexer thatincludes an acoustic wave filter according to an embodiment. FIG. 27E isa schematic diagram of a multiplexer that includes an acoustic wavefilter according to an embodiment.

FIGS. 28, 29, 30, 31, and 32 are schematic block diagrams ofillustrative packaged modules according to certain embodiments.

FIG. 33 is a schematic diagram of one embodiment of a mobile device.

FIG. 34 is a schematic diagram of one example of a communicationnetwork.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following description of certain embodiments presents variousdescriptions of specific embodiments. However, the innovations describedherein can be embodied in a multitude of different ways, for example, asdefined and covered by the claims. In this description, reference ismade to the drawings where like reference numerals can indicateidentical or functionally similar elements. It will be understood thatelements illustrated in the figures are not necessarily drawn to scale.Moreover, it will be understood that certain embodiments can includemore elements than illustrated in a drawing and/or a subset of theelements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings.

BAW devices can include raised frame structures. A raised framestructure can reduce lateral energy leakage from a main acousticallyactive region of the bulk acoustic wave device.

Aspects of this disclosure relate to bulk acoustic wave (BAW) deviceswith a multi-gradient raised frame structure. Multi-gradient raisedframe structures disclosed herein can achieve high quality factor (Q)stability and reduce Q sensitivity of raised frame technology. Q of aBAW device can be improved by a combination of a multi-layer raisedframe structure and a gradient raised frame. This Q can be a Qp of theBAW device, where Qp is a quality factor at anti-resonance. Dualgradient raised frame structures disclosed herein can improve Qstability and also reduce sensitivity of the raised frame on Q. A dualgradient raised frame structure may compensate for energy reflectionfrom leakage relative to a single gradient raised frame structure.Accordingly, a dual gradient raised frame structure can provide betterperformance than a single gradient raised frame structure in certainapplications.

Embodiments disclosed herein relate to BAW devices that include amulti-layer raised frame structure with a plurality of gradients. Themulti-layer raised frame structure can include a first raised framelayer positioned between a lower electrode and an upper electrode of aBAW device. The multi-layer raised frame structure can also include asecond raised frame layer positioned over the first raised frame layer.The second raised frame layer can extend beyond the first raised framelayer. The second raised frame layer can be tapered on opposing sideswhere the second raised frame layer extends beyond the first raisedframe layer. Tapered portions of the second raised frame layer can havea taper angle that is less than 90 degrees. For example, the taper anglecan be less than 45 degrees. The multi-layer raised frame structure canhave a convex structure relative to a surface of a piezoelectric layerand/or an electrode layer. The multi-layer raised frame structure canhave a convex structure relative to an acoustic reflector, such as anair cavity. The multi-layer raised frame structure can form a domeshaped structure. The multi-layer raised frame structure can surround amain acoustically active region of a BAW device in plan view.

The first raised frame layer can have a lower acoustic impedance thanthe piezoelectric layer of a BAW device. The first raised frame layercan have a lower acoustic impedance than the lower electrode layer andthe upper electrode layer of a BAW device. The first raised frame layercan reduce a coupling coefficient. The first raised frame layer can bean oxide. The first raised frame layer can be a metal. The first raisedframe layer can be a polymer. The first raised frame layer can includeone or more of an oxide, a metal, or a polymer. The first raised framelayer can include, for example, silicon dioxide (SiO₂) layer, siliconnitride (SiN) layer, silicon carbide (SiC) layer, or any other suitablelow acoustic impedance material. Because SiO₂ is already used in avariety of bulk acoustic wave devices, a SiO₂ first raised frame layercan be relatively easy to manufacture. While the first raised framelayer may be referred to as an oxide in certain instances, the firstraised frame layer can include any suitable material for a particularapplication.

The second raised frame layer can be a relatively high acousticimpedance. For instance, the second raised frame layer can includemolybdenum (Mo), tungsten (W), ruthenium (Ru), platinum (Pt), iridium(Ir), the like, or any suitable alloy thereof. The second raised framelayer can be a metal layer. Alternatively, the second raised frame layercan be a suitable non-metal material with a relatively high acousticimpedance. The acoustic impedance of the second raised frame layer canbe similar to or higher than the acoustic impedance of an electrodelayer of the BAW device. In some instances, the second raised framelayer can be of the same material as an electrode layer of the BAWdevice. The second raised frame layer can have a relatively highdensity. While the second raised frame layer may be referred to as ametal layer or a metallic layer in certain instances, the second raisedframe layer can include any suitable material for a particularapplication.

Example BAW devices with multi-gradient raised frame structures will nowbe discussed. Any suitable principles and advantages of these BAWdevices can be implemented together with each other.

FIG. 1 is a schematic cross-sectional view of a BAW device 10 with adual gradient raised frame structure according to an embodiment. The BAWdevice 10 can generate a bulk acoustic wave. The BAW device 10 can be aBAW resonator. The illustrated BAW device 10 includes a mainacoustically active region Main Region and a frame region on opposingsides of the main acoustically active region in the illustratedcross-sectional view. Both the main acoustically active region Main andthe frame region are included over the acoustic reflector in the BAWdevice 10. There can be a significant (e.g., exponential) fall off ofacoustic energy in the piezoelectric layer for a main mode in the frameregion relative to the main acoustically active region. In the frameregion, there is a first gradient region RaF1, a non-gradient regionRaF2, and a second gradient region RaF3. The first and second gradientregions RaF1 and RaF3, respectively, are both included over the acousticreflector. As shown in FIG. 1, the first and second gradient regionsRaF1 and RaF3, respectively, are over the air cavity 18. The mainacoustically active region can be significantly larger than the frameregion. FIGS. 2A and 2B can show the relative sizes of the mainacoustically active region and the frame region more to scale than thecross-sectional view of FIG. 1.

As illustrated, the BAW device 10 includes a piezoelectric layer 11, afirst electrode 12, a second electrode 14, a first raised frame layer15, a second raised frame layer 16, a support substrate 17, an acousticreflector such as an air cavity 18, and a passivation layer 19.

The piezoelectric layer 11 is positioned between the first electrode 12and the second electrode 14. The piezoelectric layer 11 can be analuminum nitride (AlN) layer. The piezoelectric layer 11 can be anyother suitable piezoelectric layer. In the main acoustically activeregion Main Region, piezoelectric layer 11 overlaps with and is inphysical contact with both the first electrode 12 and the secondelectrode 14 over the air cavity 18. The main acoustically active regionMain Region is also free from the first and second raised frame layers15 and 16, respectively.

The first electrode 12 can have a relatively high acoustic impedance.For example, the first electrode 12 can include molybdenum (Mo),tungsten (W), ruthenium (Ru), chromium (Cr), iridium (Jr), platinum(Pt), Ir/Pt, or any suitable alloy and/or combination thereof.Similarly, the second electrode 14 can have a relatively high acousticimpedance. The second electrode 14 can include Mo, W, Ru, Ir, Cr, Pt,Ir/Pt, or any suitable alloy and/or combination thereof. The secondelectrode 14 can be formed of the same material as the first electrode14 in certain instances. The first electrode 12 can be referred to as alower electrode. The second electrode 14 can be referred to as an upperelectrode.

The first raised frame layer 15 can have a lower acoustic impedance thanthe piezoelectric layer 11 of the BAW device 10. The first raised framelayer 15 can have a lower acoustic impedance than the first electrode 12and the second electrode layer 14 of a BAW device 10. The first raisedframe layer 15 can be an oxide, such as a silicon oxide. Such a firstraised frame layer 15 can be referred to as an oxide raised frame layer.The first raised frame layer 15 can be a dielectric layer. The firstraised frame 15 layer can include a metal. The first raised frame 15layer can be a polymer. The first raised frame layer 15 can include oneor more of an oxide, a metal, or a polymer. The first raised frame layer15 can include, for example, a SiO₂ layer, a SiN layer, a SiC layer, orany other suitable low acoustic impedance material. Because SiO₂ isalready used in a variety of bulk acoustic wave devices, a SiO₂ firstraised frame layer 15 can be relatively easy to manufacture.

The second raised 16 frame layer can be a relatively high acousticimpedance material. For instance, the second raised frame 16 layer caninclude Mo, W, Ru, Ir, Cr, Pt, the like, or any suitable alloy thereof.The second raised 16 frame layer can be a metallic layer. In suchembodiments, the second raised frame layer 16 can be referred to as ametal raised frame layer. Alternatively, the second raised frame layer16 can be a suitable non-metal material with a relatively high acousticimpedance. The acoustic impedance of the second raised frame layer 16can be similar to or greater than the acoustic impedance of an electrode12 and/or 14 of the BAW device 10. In some instances, the second raisedframe layer 16 can be of the same material as an electrode 12 and/or 14of the BAW device 10. The second raised frame layer 16 can have arelatively high density. The density of the second raised frame layer 16can be similar to or heavier than the density of an electrode 12 and/or14 of the BAW device 10.

In certain embodiments, the first raised frame layer 15 is an oxidelayer (e.g., a silicon dioxide layer) and the second raised frame layer16 is a metallic layer. In at least some such embodiments, the firstraised frame layer 15 can be of the same material as the passivationlayer 19. The second raised frame layer 16 can be of the same materialas at least one of the electrodes 12 and 14 in some such instances.

In FIG. 1, the first raised frame layer 15 and the second raised framelayer 16 are both substantially parallel to the piezoelectric layer 11in the non-gradient region RaF2 of the frame region. The illustratedsecond raised frame layer 16 is tapered and extends beyond the firstraised frame layer 15 in the first and second gradient regions RaF1 andRaF3, respectively, of the frame region. The first gradient region RaF1and the second gradient region RaF3 are on opposing sides of the raisedframe structure. In the BAW device 10 shown in FIG. 1, the opposingsides are an inner side of the raised frame structure that extendstoward the main acoustically active region Main Region and an outer sideaway from the main acoustically active region Main Region. The outerside is at or near an edge of the air cavity 18 in FIG. 1. The secondraised frame layer 16 is a continuous layer extending from the firstgradient region RaF1 to the second gradient region RaF3 in the BAWdevice 10. The second raised frame layer 16 has a non-gradient portionin the non-gradient region RaF2 and gradient portions in the gradientregions RaF1 and RaF3 in FIG. 1.

Although embodiments disclosed herein may include dual gradient raisedframe structures, any suitable principles and advantages disclosedherein can be implemented in BAW devices with three or more gradientregions. While the frame region of FIG. 1 includes two gradient regionsRaF1 and RaF3 and a non-gradient region RaF2 between the gradientregions RaF1 and RaF3, some other multi-gradient raised frame structures(e.g., raised frame structures with relatively narrow width) can includegradient regions without a non-gradient region. Accordingly, amulti-gradient raised frame structure can consist of or consistessentially of gradient regions. An example of such a BAW device isshown in FIG. 21.

Any suitable principles and advantages disclosed herein can be appliedto floating raised frame structures where a raised frame structure is ata floating voltage level. The floating raised frame structure can beelectrically isolated from the electrodes of the BAW device (e.g., by adielectric material).

A frame region can surround the main acoustically active region of a BAWdevice in plan view. FIG. 2A shows an example frame region 22surrounding a main acoustically active region 21 in plan view. Thecross-sectional views in the drawings can be along the line A-A′ in FIG.2A in certain embodiments. A BAW device 20A shown in FIG. 2A has asemi-circular or semi-elliptical shape in plan view. The frame region 22shown in FIG. 2A can include any of the gradient frame regions andnon-gradient frame regions shown in any of the cross-sectional diagramsof the figures. The frame region 22 can also include one or morerecessed frame regions. A recessed frame region can be located between araised frame region and a central part of the main acoustically activeregion 21. In a recessed frame region, there can be less mass loadingthan in the main acoustically active region 21.

A BAW device in accordance with any suitable principles and advantagesdisclosed herein can alternatively have any other suitable shape in planview, such as a quadrilateral shape, a quadrilateral shape with curvedsides, a pentagon shape, a pentagon shape with curved sides, or thelike. For example, FIG. 2B shows another example of another BAW device20B with a frame region 22 surrounding a main acoustically active region21 in plan view. The BAW device 20B shown in FIG. 2B has a pentagonshape with rounded sides in plan view. The cross-sectional views in thedrawings can be along the line B-B′ in FIG. 2B in certain embodiments.The frame region 22 shown in FIG. 2B can include any of the gradientframe regions and non-gradient frame regions shown in any of thecross-sectional diagrams of the figures. The frame region 22 of the BAWdevice 20B can also include one or more recessed frame regions locatedbetween a raised frame region and a central part of the mainacoustically active region 21.

FIG. 3A shows a cross sectional view of a BAW device 30 with a dualgradient raised frame structure. FIG. 3B shows simulation results forthe BAW device 30 of FIG. 3A where mirrored versions of the circled dualgradient raised frame structure are included on opposing sides of thecross-sectional view of the BAW device 30. The simulation results arefor Q as slope and thickness of a silicon dioxide first raised framelayer 15 are varied. The simulation results show a large region where ahigh Q value is achieved. These simulation results indicate that astable Q can be achieved in the presence of process changes and/orprocess variations. For example, the simulation results indicate thatthickness of the first raised frame layer 15 of FIG. 3A can be adjustedwithout a significant impact on Q.

FIG. 4A shows a cross sectional view of a portion of a BAW device 40with a single gradient raised frame structure circled. In the BAW device40, the single gradient on an inner side of the raised frame structurethat extends to the main acoustically active region. The outer side ofthe raised frame structure of the BAW device 40 near an edge of the aircavity 18 does not include a gradient. FIG. 4B shows simulation resultsfor the BAW device 40 of FIG. 4A where mirrored versions of the circledsingle gradient raised frame structure are included on opposing sides ofthe cross-section of the BAW device 40. The simulation results are for Qas slope and thickness of a silicon dioxide first raised frame layer 15are varied. The simulation results indicate that the simulated BAWdevice 40 can achieve a high Q. These simulation results also indicate aless stable Q compared to the BAW device 30 of FIG. 3A as deviceparameters, such as thickness of the first raised frame layer 15,change.

FIG. 5A shows a cross sectional view of a portion of a BAW device 50with a raised frame structure without the second raised frame layer 16extending beyond the first raised frame layer 15 toward the mainacoustically active region circled. FIG. 5B shows simulation results forthe BAW device 50 of FIG. 5A where mirrored versions of the circledraised frame structure are included on opposing sides of thecross-section of the BAW device 50. The simulation results are for Q asslope and thickness of a silicon dioxide first raised frame layer 15 arevaried. The simulation results indicate that the simulated BAW device 50has less desirable Q performance relative to the BAW devices 30 and 40corresponding to the simulation results in FIGS. 3B and 4B,respectively. Having the second raised frame layer 16 extend beyond thefirst raised frame layer on opposing sides of a raised frame structurecan be desirable.

The BAW device 10 of FIG. 1 is a film bulk acoustic resonator (FBAR).The principles and advantages disclosed herein can be applied to otherBAW devices. FIG. 6 illustrates a solidly mounted resonator (SMR) BAWdevice 60 with a dual gradient raised frame structure. The SMR BAWdevice 60 includes a solid acoustic mirror 62 in place of an air cavityas an acoustic reflector. The solid acoustic mirror 62 is an acousticBragg reflector. The solid acoustic mirror 62 includes alternating lowacoustic impedance layers 63 and high acoustic impedance layers 64. Asone example, the solid acoustic mirror 62 can include alternatingsilicon dioxide layers as low acoustic impedance layers 63 and tungstenlayers as high acoustic impedance layers 64. Any suitable principles andadvantages disclosed herein can be applied to SMR BAW devices.

FIGS. 7 to 21 are cross-sectional views of embodiments of BAW deviceswith multi-gradient raised frame structures. In these drawings, asupport substrate under an acoustic reflector (e.g., air cavity) is notshown although the support substrate is included below the acousticreflector in these embodiments. Any suitable combination of features ofthese embodiments can be implemented together with each other and/orother embodiments disclosed herein.

FIG. 7 is a schematic cross-sectional view of a BAW device 70 with amulti-gradient raised frame structure according to an embodiment. Asshown in FIG. 7, the second raised frame layer 16 can extend beyond thefirst raised frame layer 15 on only one side of the first raised framelayer 15 for a first part 72 of a BAW device 70 and extend beyond bothsides of the first raised frame layer 15 for a second part 74 of the BAWdevice 70. The first part 72 and the second part 74 of the BAW device 70can be on opposite sides of the main acoustically active region as shownin FIG. 7.

FIG. 8 is a schematic cross-sectional view of a BAW device 80 with amulti-gradient raised frame structure according to an embodiment. InFIG. 8, the first raised frame layer 15 is included on one side of theBAW device in the illustrated schematic cross-sectional view. Asillustrated, the multi-gradient raised frame structure of the BAW device80 includes a multi-layer part 82 and single layer part 84. The BAWdevice 80 is an example of a multi-gradient raised frame BAW devicewhere a raised frame layer (i.e., the first raised frame layer 15 pf theBAW device 80) is included along only part of the main acousticallyactive region of the BAW device.

FIG. 9 is a schematic cross-sectional view of a BAW device 90 with amulti-gradient raised frame structure according to an embodiment. InFIG. 9, one side of the cross-sectional view includes a single raisedframe layer in a first part 92 of the BAW device 90 and a second side ofthe cross-sectional view includes a dual layer raised frame layer in asecond part 94 of the BAW device 90 where the second layer extendsbeyond the first layer on one side. The raised frame structure of theBAW device 90 includes a multi-layer part 94 and single layer part 92.In multi-layer part 94 of the multi-gradient raised frame structure, thesecond raised frame layer 16 extends beyond first raised frame layer 15on only one side. In the single layer part 92 of the multi-gradientraised frame structure, a portion of the second raised frame layer 16 isthicker than in the multi-layer part 94 of the multi-gradient raisedframe structure in the BAW device 90. In the non-gradient region of thesingle layer part 92, the second raised frame layer 16 is thicker thanin the multi-layer part 94.

Although some multi-gradient raised frame BAW devices disclosed hereininclude a plurality of raised frame layers, multi-gradient raised frameBAW devices can include a single raised frame layer. FIGS. 10, 11, and12 illustrate examples of such BAW devices.

FIG. 10 illustrates a schematic cross-sectional view of a BAW device 100with a single layer raised frame structure according to an embodiment.The raised frame layer 16 is asymmetric about the center of the mainacoustically active region of the BAW device 100 in the illustratedview. The BAW device 100 includes a multi-gradient raised framestructure with single raised frame layer. The single raised frame layer16 corresponds to the second raised frame layer 16 of other BAW devicesdisclosed herein. The raised frame layer 16 can be considered a singlelayer even if it is formed of several layers of the same material. Theraised frame layer 16 of the BAW device 100 can be of the same materialas the electrode 14 in certain embodiments. The raised frame layer 16 ofthe BAW device 100 can have a relatively high acoustic impedance.

FIG. 11 illustrates a schematic cross-sectional view of a BAW device 110with a single layer raised frame structure according to an embodiment.In the BAW device 110, the raised frame layer 15 corresponds to thefirst raised frame layer 15 of other embodiments. The single layerraised frame layer 15 of the BAW device 110 can be of the same materialas the passivation layer 19 in certain embodiments. The raised framelayer 15 of the BAW device 110 can have a relatively low acousticimpedance that is lower than the acoustic impedance of the electrodes 12and 14 and/or the piezoelectric layer 11. As illustrated, the raisedframe layer 15 is positioned between the piezoelectric layer 11 and theelectrode 14. In some other embodiments, the raised frame layer 15 canalternatively or additionally be positioned between the piezoelectriclayer 11 and the electrode 12.

FIG. 12 illustrates a schematic cross-sectional view of a BAW device 120according to an embodiment. The BAW device 120 includes a dual gradientraised frame structure where the raised frame structure is positionedbetween the piezoelectric layer 11 and the lower electrode 12. In theBAW device 120, the raised frame structure includes a single raisedframe layer 16. The raised frame layer 16 of the BAW device 120corresponds to the second raised frame layer 16 of BAW devices of otherembodiments. As illustrated in FIG. 12, the raised frame layer ispositioned between electrodes 12 and 14.

FIG. 13 illustrates a schematic cross-sectional view of a BAW device 130according to an embodiment. The BAW device 130 includes a dual gradientraised frame structure where the raised frame structure includes twolayers positioned between the piezoelectric layer 11 and the lowerelectrode 12. The dual gradient raised frame structure is positionedbetween the electrodes 12 and 14 in the BAW device 130. In the BAWdevice 130, the first raised frame layer 15 is positioned between theelectrode 12 and the second raised frame structure 16. The second raisedframe layer 16 includes a portion between the first raised frame layer15 and the piezoelectric layer in the BAW device 130. The second raisedframe layer 16 extends beyond the first raised frame layer 15 onopposing sides in FIG. 13.

FIG. 14 illustrates a schematic cross-sectional view of a BAW device 140according to an embodiment. The BAW device 140 includes a dual gradientraised frame structure where the raised frame structure includes twolayers positioned between the electrodes 12 and 14 on opposing sides ofthe piezoelectric layer 11. In the BAW device 140, the piezoelectriclayer 11 is positioned between the first raised frame layer 15 and thesecond raised frame layer 16, and the first raised frame layer 15 andthe second raised frame layer 16 are both positioned between theelectrodes 12 and 14. In the BAW device 140, the second raised framelayer 16 extends beyond the first raised frame layer 15 on opposingsides. The second raised frame layer 16 is positioned between thepiezoelectric layer 11 and the second electrode 14 in the BAW device140. The first raised frame layer 15 is positioned between thepiezoelectric layer 11 and the first electrode 12 in the BAW device 140.

FIG. 15 illustrates a schematic cross-sectional view of a BAW device 150according to an embodiment. The BAW device 150 includes a dual gradientraised frame structure where the raised frame structure includes twolayers positioned between the electrodes 12 and 14 on opposing sides ofthe piezoelectric layer 11. In the BAW device 150, the second raisedframe layer 16 extends beyond the first raised frame layer 15 on aninner side of the raised frame structure toward the main acousticallyactive region. The second raised frame layer 16 does not extend beyondthe first raised frame layer 15 on an outer side of the raised framestructure opposite the main acoustically active region in the BAW device150. The second raised frame layer 16 is positioned between thepiezoelectric layer 11 and the first electrode 12 over the acousticreflector in the BAW device 150. The first raised frame layer 15 ispositioned between the piezoelectric layer 11 and the second electrode14 in the BAW device 150.

Embodiments disclosed herein relate to a multi-layer raised framestructure configured to reduce lateral energy leakage from a mainacoustically active region of the bulk acoustic wave device, where alayer of the multi-layer raised frame structure is embedded in thepiezoelectric layer. Example embodiments with a raised frame layerembedded in a piezoelectric layer will be discussed with reference toFIGS. 16, 18, and 20.

FIG. 16 illustrates a schematic cross-sectional view of a BAW device 160according to an embodiment. The BAW device 160 includes a dual layerraised frame structure with a raised frame layer 15 embedded in thepiezoelectric layer 11. The piezoelectric layer 11 can include differentmaterial on opposing sides of the embedded raised frame layer 15 incertain applications. For instance, on one side of the embedded raisedframe layer 15 the piezoelectric layer 11 can include AlN, and thepiezoelectric layer 11 can include AlN doped with scandium on anopposite side of the embedded raised frame layer 15. In certaininstances, the piezoelectric layer 11 includes the same material onopposing sides of the embedded raised frame structure. In the BAW device160, the second raised frame layer 16 extends beyond the first raisedframe layer 15 on inner side of raised frame structure toward mainacoustically active region of the BAW device 160. The second raisedframe layer 16 does not extend beyond the first raised frame layer 15 onan outer side of the raised frame structure opposite the mainacoustically active region in the BAW device 160.

FIG. 17 illustrates a schematic cross-sectional view of a BAW device 170with a multi-layer raised frame structure with gradients according to anembodiment. In the BAW device 170, the first raised frame layer 16 isembedded in the piezoelectric layer 11. The BAW device 170 is similar tothe BAW device 160 of FIG. 16, except that the first raised frame layer15 is positioned between the piezoelectric layer 11 and the firstelectrode 12 over the acoustic reflector in the BAW device 160.

FIG. 18 illustrates a schematic cross-sectional view of a BAW device 180with a dual gradient raised frame structure with a raised frame layer 15embedded in the piezoelectric layer 11 according to an embodiment. TheBAW device 180 is similar to the BAW device 10 of FIG. 1, except thatthe first raised frame layer 15 is embedded in the piezoelectric layer11 in the BAW device 180.

FIG. 19 illustrates a schematic cross-sectional view of a BAW device 190with a dual gradient raised frame structure according to an embodiment.The BAW device 190 is similar to the BAW device 10 of FIG. 1, exceptthat the first raised frame layer 15 is positioned between thepiezoelectric layer 11 and the first electrode 12 in the BAW device 190.The BAW device 190 is similar to the BAW device 170 of FIG. 17, exceptthat the second raised frame layer 16 extends beyond the first raisedframe layer 15 on both an inner side and an outer side of the raisedframe structure in the BAW device 190.

FIG. 20 illustrates a schematic cross-sectional view of a BAW device 200according to an embodiment. In certain applications, a multi-gradientraised frame structure can be embedded in a piezoelectric layer 11. TheBAW device 200 includes a dual gradient raised frame structure where twolayers 15 and 16 of the raised frame structure are embedded in thepiezoelectric layer 11.

FIG. 21 illustrates a schematic cross-sectional view of a BAW device 210according to an embodiment. The BAW device 210 is an example of a BAWdevice with a multi-gradient raised frame structure that consists orconsists essentially of gradient regions RaF1 and RaF3. In such a BAWdevice, the raised frame structure can have a relatively narrow widthover the acoustic reflector.

A gradient portion of a raised frame layer can have a taper angle a withrespect to a horizontal direction in the illustrated schematiccross-sectional views. The taper angle a can be with respect to anunderlying layer (e.g., a piezoelectric layer and/or an electrodelayer). FIG. 22 illustrates a taper angle a. The taper angle a can beless than 45°. In some applications, the taper angle can be less than45° for a gradient portion of a raised frame layer in a first gradientregion RaF1. The taper angle can also be greater than 5° in a firstgradient region RaF1 in such applications. In some instances, the taperangle can be in a range from about 5° to 45° for a gradient portion of araised frame layer in a first gradient region RaF1. In someapplications, the taper angle can be less than 45° for a gradientportion of a raised frame layer in a second gradient region RaF3 of anyof the embodiments disclosed herein. The taper angle can also be greaterthan 5° in a second gradient region RaF3 in such applications. In someinstances, the taper angle can be in a range from about 5° to 45° for agradient portion of a raised frame layer in a second gradient regionRaF3 of any of the embodiments disclosed herein.

In certain applications, the taper angle can be in a range from about10° to 40° for a gradient portion of a raised frame layer in a firstgradient region RaF1 and/or a second gradient region RaF3 of any of theembodiments disclosed herein. In some applications, the taper angle canbe in a range from about 10° to 30° for a gradient portion of a raisedframe layer in a first gradient region RaF1 and/or a second gradientregion RaF3 of any of the embodiments disclosed herein.

The taper angles can be approximately the same for the first and secondgradient regions RaF1 and RaF3 in certain applications. The taper anglescan be different for the first and second gradient regions RaF1 and RaF3in some other applications. The taper angles discussed in this paragraphcan be applied to any suitable BAW devices disclosed herein.

FIG. 23 illustrates examples gradient portions of a raised frame layerwhere the gradient portion can be non-linear. A non-linear gradientportion can include a convex portion, a concave portion, or anycombination thereof. Other variations of gradient raised frame layerportions are possible.

BAW devices disclosed herein can be implemented as BAW resonators in inacoustic wave filters. Such filters can be arranged to filter a radiofrequency signal. In certain applications, the acoustic wave filters canbe band pass filters arranged to pass a radio frequency band andattenuate frequencies outside of the radio frequency band. Acoustic wavefilters can implement band rejection filters. Bulk acoustic wave devicesdisclosed herein can be implemented in a variety of different filtertopologies. Example filter topologies include a ladder filter, a latticefilter, and a hybrid ladder lattice filter, and the like. An acousticwave filter can include all BAW resonators or one or more BAW resonatorsand one or more other types of acoustic wave resonators such as a SAWresonator. BAW resonators disclosed herein can be implemented in afilter that includes at least one BAW resonator and a non-acousticinductor-capacitor component. Some example filter topologies will now bediscussed with reference to FIGS. 24 to 26. Any suitable combination offeatures of the filter topologies of FIGS. 24 to 26 can be implementedtogether with each other and/or with other filter topologies.

FIG. 24 is a schematic diagram of a ladder filter 240 that includes abulk acoustic wave resonator according to an embodiment. The ladderfilter 240 is an example topology that can implement a band pass filterformed from acoustic wave resonators. In a band pass filter with aladder filter topology, the shunt resonators can have lower resonantfrequencies than the series resonators. The ladder filter 240 can bearranged to filter a radio frequency signal. As illustrated, the ladderfilter 240 includes series acoustic wave resonators R1, R3, R5, and R7and shunt acoustic wave resonators R2, R4, R6, and R8 coupled between afirst input/output port I/O₁ and a second input/output port 1102. Anysuitable number of series acoustic wave resonators can be in included ina ladder filter. Any suitable number of shunt acoustic wave resonatorscan be included in a ladder filter. The first input/output port I/O₁ cana transmit port and the second input/output port 1102 can be an antennaport. Alternatively, first input/output port I/O₁ can be a receive portand the second input/output port 1102 can be an antenna port.

One or more of the acoustic wave resonators of the ladder filter 240 caninclude a bulk acoustic wave filter according to an embodiment. Forexample, some or all of the shunt resonators R2, R4, R6, and R8 can be amulti-gradient raised frame BAW resonator in accordance with anysuitable principles and advantages disclosed herein. The anti-resonantfrequency of the shunt resonators of the ladder filter 240 can set alower edge of the pass band when the ladder filter 240 is a band passfilter. With multi-gradient raised frame BAW shunt resonators, highquality factor stability for a quality factor at anti-resonance Qp canadvantageously be achieved, for example, as indicated by the graph ofFIG. 3B. Alternatively or additionally, one or more of the seriesresonators of the ladder filter 240 can be implemented in accordancewith any suitable principles and advantages disclosed herein.

FIG. 25 is a schematic diagram of a lattice filter 250 that includes abulk acoustic wave resonator according to an embodiment. The latticefilter 250 is an example topology that can form a band pass filter fromacoustic wave resonators. The lattice filter 250 can be arranged tofilter an RF signal. As illustrated, the lattice filter 250 includesacoustic wave resonators RL1, RL2, RL3, and RL4. The acoustic waveresonators RL1 and RL2 are series resonators. The acoustic waveresonators RL3 and RL4 are shunt resonators. The illustrated latticefilter 250 has a balanced input and a balanced output. One or more ofthe illustrated acoustic wave resonators RL1 to RL4 can be a bulkacoustic wave resonator in accordance with any suitable principles andadvantages disclosed herein.

FIG. 26 is a schematic diagram of a hybrid ladder and lattice filter 260that includes a bulk acoustic wave resonator according to an embodiment.The illustrated hybrid ladder and lattice filter 260 includes seriesacoustic resonators RL1, RL2, RH3, and RH4 and shunt acoustic resonatorsRL3, RL4, RH1, and RH2. The hybrid ladder and lattice filter 260includes one or more bulk acoustic wave resonators in accordance withany suitable principles and advantages disclosed herein.

In some applications, a bulk acoustic wave resonator can be included infilter that also includes one or more inductors and one or morecapacitors.

The principles and advantages disclosed herein can be implemented in astandalone filter and/or in one or more filters in any suitablemultiplexer. Such filters can be any suitable topology discussed herein,such as any filter topology in accordance with any suitable principlesand advantages disclosed with reference to any of FIG. 21. The filtercan be a band pass filter arranged to filter a fourth generation (4G)Long Term Evolution (LTE) band and/or a fifth generation (5G) New Radio(NR) band. Examples of a standalone filter and multiplexers will bediscussed with reference to FIGS. 27A to 27E. Any suitable principlesand advantages of these filters and/or multiplexers can be implementedtogether with each other. Moreover, the multi-gradient raised frame bulkacoustic bulk acoustic wave resonators disclosed herein can be includedin filter that also includes one or more inductors and one or morecapacitors.

FIG. 27A is schematic diagram of an acoustic wave filter 330. Theacoustic wave filter 330 is a band pass filter. The acoustic wave filter330 is arranged to filter a radio frequency signal. The acoustic wavefilter 330 includes a plurality of acoustic wave resonators coupledbetween a first input/output port RF_IN and a second input/output portRF_OUT. The acoustic wave filter 330 includes one or more BAW resonatorswith a multi-gradient raised frame structure implemented in accordancewith any suitable principles and advantages disclosed herein.

FIG. 27B is a schematic diagram of a duplexer 332 that includes anacoustic wave filter according to an embodiment. The duplexer 332includes a first filter 330A and a second filter 330B coupled totogether at a common node COM. One of the filters of the duplexer 332can be a transmit filter and the other of the filters of the duplexer332 can be a receive filter. In some other instances, such as in adiversity receive application, the duplexer 332 can include two receivefilters. Alternatively, the duplexer 332 can include two transmitfilters. The common node COM can be an antenna node.

The first filter 330A is an acoustic wave filter arranged to filter aradio frequency signal. The first filter 330A includes acoustic waveresonators coupled between a first radio frequency node RF1 and thecommon node COM. The first radio frequency node RF1 can be a transmitnode or a receive node. The first filter 330A includes one or more BAWresonators with a multi-gradient raised frame structure implemented inaccordance with any suitable principles and advantages disclosed herein.

The second filter 330B can be any suitable filter arranged to filter asecond radio frequency signal. The second filter 330B can be, forexample, an acoustic wave filter, an acoustic wave filter that includesone or more BAW resonators with a multi-gradient raised frame structureimplemented in accordance with any suitable principles and advantagesdisclosed herein, an LC filter, a hybrid acoustic wave LC filter, or thelike. The second filter 330B is coupled between a second radio frequencynode RF2 and the common node. The second radio frequency node RF2 can bea transmit node or a receive node.

Although example embodiments may be discussed with filters or duplexersfor illustrative purposes, any suitable principles and advantagesdisclosed herein can be implemented in a multiplexer that includes aplurality of filters coupled together at a common node. Examples ofmultiplexers include but are not limited to a duplexer with two filterscoupled together at a common node, a triplexer with three filterscoupled together at a common node, a quadplexer with four filterscoupled together at a common node, a hexaplexer with six filters coupledtogether at a common node, an octoplexer with eight filters coupledtogether at a common node, or the like. Multiplexers can include filtershaving different passbands. Multiplexers can include any suitable numberof transmit filters and any suitable number of receive filters. Forexample, a multiplexer can include all receive filters, all transmitfilters, or one or more transmit filters and one or more receivefilters. One or more filters of a multiplexer can include any suitablenumber of BAW resonators with a multi-gradient raised frame structure.

FIG. 27C is a schematic diagram of a multiplexer 334 that includes anacoustic wave filter according to an embodiment. The multiplexer 334includes a plurality of filters 330A to 330N coupled together at acommon node COM. The plurality of filters can include any suitablenumber of filters including, for example, 3 filters, 4 filters, 5filters, 6 filters, 7 filters, 8 filters, or more filters. Some or allof the plurality of acoustic wave filters can be acoustic wave filters.As illustrated, the filters 330A to 330N each have a fixed electricalconnection to the common node COM. This can be referred to as hardmultiplexing or fixed multiplexing. Filters have fixed electricalconnections to the common node in hard multiplexing applications. Eachof the filters 330A to 330N has a respective input/output node RF1 toRFN.

The first filter 330A is an acoustic wave filter arranged to filter aradio frequency signal. The first filter 330A can include one or moreacoustic wave devices coupled between a first radio frequency node RF1and the common node COM. The first radio frequency node RF1 can be atransmit node or a receive node. The first filter 330A includes one ormore BAW resonators with a multi-gradient raised frame structure inaccordance with any suitable principles and advantages disclosed herein.The other filter(s) of the multiplexer 334 can include one or moreacoustic wave filters, one or more acoustic wave filters that includeone or more BAW resonators with a multi-gradient raised frame structure,one or more LC filters, one or more hybrid acoustic wave LC filters, orany suitable combination thereof.

FIG. 27D is a schematic diagram of a multiplexer 336 that includes anacoustic wave filter according to an embodiment. The multiplexer 336 islike the multiplexer 334 of FIG. 27C, except that the multiplexer 336implements switched multiplexing. In switched multiplexing, a filter iscoupled to a common node via a switch. In the multiplexer 336, theswitches 337A to 337N can selectively electrically connect respectivefilters 330A to 330N to the common node COM. For example, the switch337A can selectively electrically connect the first filter 330A to thecommon node COM via the switch 337A. Any suitable number of the switches337A to 337N can electrically a respective filters 330A to 330N to thecommon node COM in a given state. Similarly, any suitable number of theswitches 337A to 337N can electrically isolate a respective filter 330Ato 330N to the common node COM in a given state. The functionality ofthe switches 337A to 337N can support various carrier aggregations.

FIG. 27E is a schematic diagram of a multiplexer 338 that includes anacoustic wave filter according to an embodiment. The multiplexer 338illustrates that a multiplexer can include any suitable combination ofhard multiplexed and switched multiplexed filters. One or more BAWresonators with a multi-gradient raised frame structure can be includedin a filter that is hard multiplexed to the common node of amultiplexer. Alternatively or additionally, one or more BAW resonatorswith a multi-gradient raised frame structure can be included in a filterthat is switch multiplexed to the common node of a multiplexer.

BAW resonators disclosed herein can be implemented in a variety ofpackaged modules. Some example packaged modules will now be discussed inwhich any suitable principles and advantages of the BAW devicesdisclosed herein can be implemented. Example packaged modules includeone or more acoustic wave filters and one or more radio frequencyamplifiers (e.g., one or more power amplifiers and/or one or more lownoise amplifiers) and/or one or more radio frequency switches. Theexample packaged modules can include a package that encloses theillustrated circuit elements. The illustrated circuit elements can bedisposed on a common packaging substrate. The packaging substrate can bea laminate substrate, for example. FIGS. 28 to 32 are schematic blockdiagrams of illustrative packaged modules according to certainembodiments. Any suitable combination of features of these packagedmodules can be implemented with each other. While duplexers areillustrated in the example packaged modules of FIGS. 29 to 32, any othersuitable multiplexer that includes a plurality of filters coupled to acommon node can be implemented instead of one or more duplexers. Forexample, a quadplexer can be implemented in certain applications.Alternatively or additionally, one or more filters of a packaged modulecan be arranged as a transmit filter or a receive filter that is notincluded in a multiplexer.

FIG. 28 is a schematic diagram of a radio frequency module 340 thatincludes an acoustic wave component 342 according to an embodiment. Theillustrated radio frequency module 340 includes the acoustic wavecomponent 342 and other circuitry 343. The acoustic wave component 342can include one or more BAW resonators with a multi-gradient raisedframe structure in accordance with any suitable combination of featuresdisclosed herein. The acoustic wave component 342 can include a BAW diethat includes BAW resonators.

The acoustic wave component 342 shown in FIG. 28 includes a filter 344and terminals 345A and 345B. The filter 344 includes one or more BAWresonators implemented in accordance with any suitable principles andadvantages disclosed herein. The terminals 345A and 344B can serve, forexample, as an input contact and an output contact. The acoustic wavecomponent 342 and the other circuitry 343 are on a common packagingsubstrate 346 in FIG. 28. The packaging substrate 346 can be a laminatesubstrate. The terminals 345A and 345B can be electrically connected tocontacts 347A and 347B, respectively, on the packaging substrate 346 byway of electrical connectors 348A and 348B, respectively. The electricalconnectors 348A and 348B can be bumps or wire bonds, for example.

The other circuitry 343 can include any suitable additional circuitry.For example, the other circuitry can include one or more one or moreradio frequency amplifiers (e.g., one or more power amplifiers and/orone or more low noise amplifiers), one or more power amplifiers, one ormore radio frequency switches, one or more additional filters, one ormore low noise amplifiers, one or more RF couplers, one or more delaylines, one or more phase shifters, the like, or any suitable combinationthereof. The other circuitry 343 can be electrically connected to thefilter 344. The radio frequency module 340 can include one or morepackaging structures to, for example, provide protection and/orfacilitate easier handling of the radio frequency module 340. Such apackaging structure can include an overmold structure formed over thepackaging substrate 340. The overmold structure can encapsulate some orall of the components of the radio frequency module 340.

FIG. 29 is a schematic block diagram of a module 350 that includesduplexers 351A to 351N and an antenna switch 352. One or more filters ofthe duplexers 351A to 351N can include one or more BAW resonators with amulti-gradient raised frame structure in accordance with any suitableprinciples and advantages discussed herein. Any suitable number ofduplexers 351A to 351N can be implemented. The antenna switch 352 canhave a number of throws corresponding to the number of duplexers 351A to351N. The antenna switch 352 can include one or more additional throwscoupled to one or more filters external to the module 350 and/or coupledto other circuitry. The antenna switch 352 can electrically couple aselected duplexer to an antenna port of the module 350.

FIG. 30 is a schematic block diagram of a module 354 that includes apower amplifier 355, a radio frequency switch 356, and multiplexers 351Ato 351N in accordance with one or more embodiments. The power amplifier355 can amplify a radio frequency signal. The radio frequency switch 356can be a multi-throw radio frequency switch. The radio frequency switch356 can electrically couple an output of the power amplifier 355 to aselected transmit filter of the multiplexers 351A to 351N. One or morefilters of the multiplexers 351A to 351N can include any suitable numberof BAW resonators with a multi-gradient raised frame structure inaccordance with any suitable principles and advantages discussed herein.Any suitable number of multiplexers 351A to 351N can be implemented.

FIG. 31 is a schematic block diagram of a module 357 that includesmultiplexers 351A′ to 351N′, a radio frequency switch 358, and a lownoise amplifier 359 according to an embodiment. One or more filters ofthe multiplexers 351A′ to 351N′ can include any suitable number BAWresonators with a multi-gradient raised frame structure in accordancewith any suitable principles and advantages disclosed herein. Anysuitable number of multiplexers 351A′ to 351N′ can be implemented. Theradio frequency switch 358 can be a multi-throw radio frequency switch.The radio frequency switch 358 can electrically couple an output of aselected filter of multiplexers 351A′ to 351N′ to the low noiseamplifier 359. In some embodiments (not illustrated), a plurality of lownoise amplifiers can be implemented. The module 357 can includediversity receive features in certain applications.

FIG. 32 is a schematic diagram of a radio frequency module 380 thatincludes an acoustic wave filter according to an embodiment. Asillustrated, the radio frequency module 380 includes duplexers 382A to382N that include respective transmit filters 383A1 to 383N1 andrespective receive filters 383A2 to 383N2, a power amplifier 384, aselect switch 385, and an antenna switch 386. The radio frequency module380 can include a package that encloses the illustrated elements. Theillustrated elements can be disposed on a common packaging substrate387. The packaging substrate 387 can be a laminate substrate, forexample. A radio frequency module that includes a power amplifier can bereferred to as a power amplifier module. A radio frequency module caninclude a subset of the elements illustrated in FIG. 32 and/oradditional elements. The radio frequency module 380 may include one ormore BAW resonators with a multi-gradient raised frame structure inaccordance with any suitable principles and advantages disclosed herein.

The duplexers 382A to 382N can each include two acoustic wave filterscoupled to a common node. For example, the two acoustic wave filters canbe a transmit filter and a receive filter. As illustrated, the transmitfilter and the receive filter can each be a band pass filter arranged tofilter a radio frequency signal. One or more of the transmit filters383A1 to 383N1 can include one or more BAW resonators with amulti-gradient raised frame structure in accordance with any suitableprinciples and advantages disclosed herein. Similarly, one or more ofthe receive filters 383A2 to 383N2 can include one or more BAWresonators with a multi-gradient raised frame structure in accordancewith any suitable principles and advantages disclosed herein. AlthoughFIG. 32 illustrates duplexers, any suitable principles and advantagesdisclosed herein can be implemented in other multiplexers (e.g.,quadplexers, hexaplexers, octoplexers, etc.) and/or in switchedmultiplexers.

The power amplifier 384 can amplify a radio frequency signal. Theillustrated switch 385 is a multi-throw radio frequency switch. Theswitch 385 can electrically couple an output of the power amplifier 384to a selected transmit filter of the transmit filters 383A1 to 383N1. Insome instances, the switch 385 can electrically connect the output ofthe power amplifier 384 to more than one of the transmit filters 383A1to 383N1. The antenna switch 386 can selectively couple a signal fromone or more of the duplexers 382A to 382N to an antenna port ANT. Theduplexers 382A to 382N can be associated with different frequency bandsand/or different modes of operation (e.g., different power modes,different signaling modes, etc.).

BAW devices with a multi-gradient raised frame structure disclosedherein can be implemented in a variety of wireless communicationdevices, such as mobile devices. One or more filters with any suitablenumber of BAW devices implemented with any suitable principles andadvantages disclosed herein can be included in a variety of wirelesscommunication devices, such as mobile phones. The BAW devices can beincluded in a filter of a radio frequency front end. FIG. 33 is aschematic diagram of one embodiment of a mobile device 390. The mobiledevice 390 includes a baseband system 391, a transceiver 392, a frontend system 393, antennas 394, a power management system 395, a memory396, a user interface 397, and a battery 398.

The mobile device 390 can be used communicate using a wide variety ofcommunications technologies, including, but not limited to, secondgeneration (2G), third generation (3G), fourth generation (4G)(including LTE, LTE-Advanced, and LTE-Advanced Pro), fifth generation(5G) New Radio (NR), wireless local area network (WLAN) (for instance,WiFi), wireless personal area network (WPAN) (for instance, Bluetoothand ZigBee), WMAN (wireless metropolitan area network) (for instance,WiMax), Global Positioning System (GPS) technologies, or any suitablecombination thereof.

The transceiver 392 generates RF signals for transmission and processesincoming RF signals received from the antennas 394. It will beunderstood that various functionalities associated with the transmissionand receiving of RF signals can be achieved by one or more componentsthat are collectively represented in FIG. 33 as the transceiver 392. Inone example, separate components (for instance, separate circuits ordies) can be provided for handling certain types of RF signals.

The front end system 393 aids in conditioning signals transmitted toand/or received from the antennas 394. In the illustrated embodiment,the front end system 393 includes antenna tuning circuitry 400, poweramplifiers (PAs) 401, low noise amplifiers (LNAs) 402, filters 403,switches 404, and signal splitting/combining circuitry 405. However,other implementations are possible. One or more of the filters 403 canbe implemented in accordance with any suitable principles and advantagesdisclosed herein. For example, one or more of the filters 403 caninclude at least one BAW resonator with a multi-gradient raised framestructure in accordance with any suitable principles and advantagesdisclosed herein.

For example, the front end system 393 can provide a number offunctionalities, including, but not limited to, amplifying signals fortransmission, amplifying received signals, filtering signals, switchingbetween different bands, switching between different power modes,switching between transmission and receiving modes, duplexing ofsignals, multiplexing of signals (for instance, diplexing ortriplexing), or any suitable combination thereof.

In certain implementations, the mobile device 390 supports carrieraggregation, thereby providing flexibility to increase peak data rates.Carrier aggregation can be used for both Frequency Division Duplexing(FDD) and Time Division Duplexing (TDD), and may be used to aggregate aplurality of carriers or channels. Carrier aggregation includescontiguous aggregation, in which contiguous carriers within the sameoperating frequency band are aggregated. Carrier aggregation can also benon-contiguous, and can include carriers separated in frequency within acommon band or in different bands.

The antennas 394 can include antennas used for a wide variety of typesof communications. For example, the antennas 394 can include antennasfor transmitting and/or receiving signals associated with a wide varietyof frequencies and communications standards.

In certain implementations, the antennas 394 support MIMO communicationsand/or switched diversity communications. For example, MIMOcommunications use multiple antennas for communicating multiple datastreams over a single radio frequency channel. MIMO communicationsbenefit from higher signal to noise ratio, improved coding, and/orreduced signal interference due to spatial multiplexing differences ofthe radio environment. Switched diversity refers to communications inwhich a particular antenna is selected for operation at a particulartime. For example, a switch can be used to select a particular antennafrom a group of antennas based on a variety of factors, such as anobserved bit error rate and/or a signal strength indicator.

The mobile device 390 can operate with beamforming in certainimplementations. For example, the front end system 393 can includeamplifiers having controllable gain and phase shifters havingcontrollable phase to provide beam formation and directivity fortransmission and/or reception of signals using the antennas 394. Forexample, in the context of signal transmission, the amplitude and phasesof the transmit signals provided to the antennas 394 are controlled suchthat radiated signals from the antennas 394 combine using constructiveand destructive interference to generate an aggregate transmit signalexhibiting beam-like qualities with more signal strength propagating ina given direction. In the context of signal reception, the amplitude andphases are controlled such that more signal energy is received when thesignal is arriving to the antennas 394 from a particular direction. Incertain implementations, the antennas 394 include one or more arrays ofantenna elements to enhance beamforming.

The baseband system 391 is coupled to the user interface 397 tofacilitate processing of various user input and output (I/O), such asvoice and data. The baseband system 391 provides the transceiver 392with digital representations of transmit signals, which the transceiver392 processes to generate RF signals for transmission. The basebandsystem 391 also processes digital representations of received signalsprovided by the transceiver 392. As shown in FIG. 33, the basebandsystem 391 is coupled to the memory 396 to facilitate operation of themobile device 390.

The memory 396 can be used for a wide variety of purposes, such asstoring data and/or instructions to facilitate the operation of themobile device 390 and/or to provide storage of user information.

The power management system 395 provides a number of power managementfunctions of the mobile device 390. In certain implementations, thepower management system 395 includes a PA supply control circuit thatcontrols the supply voltages of the power amplifiers 401. For example,the power management system 395 can be configured to change the supplyvoltage(s) provided to one or more of the power amplifiers 401 toimprove efficiency, such as power added efficiency (PAE).

As shown in FIG. 33, the power management system 395 receives a batteryvoltage from the battery 398. The battery 398 can be any suitablebattery for use in the mobile device 390, including, for example, alithium-ion battery.

Technology disclosed herein can be implemented in acoustic wave filtersin 5G applications. 5G technology is also referred to herein as 5G NewRadio (NR). 5G NR supports and/or plans to support a variety offeatures, such as communications over millimeter wave spectrum,beamforming capability, high spectral efficiency waveforms, low latencycommunications, multiple radio numerology, and/or non-orthogonalmultiple access (NOMA). Although such RF functionalities offerflexibility to networks and enhance user data rates, supporting suchfeatures can pose a number of technical challenges.

The teachings herein are applicable to a wide variety of communicationsystems, including, but not limited to, communication systems usingadvanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro,and/or 5G NR. An acoustic wave device including any suitable combinationof features disclosed herein be included in a filter arranged to filtera radio frequency signal in a 5G NR operating band within FrequencyRange 1 (FR1). A filter arranged to filter a radio frequency signal in a5G NR operating band can include one or more BAW devices disclosedherein. FR1 can be from 410 MHz to 7.125 GHz, for example, as specifiedin a current 5G NR specification. One or more BAW devices in accordancewith any suitable principles and advantages disclosed herein can beincluded in a filter arranged to filter a radio frequency signal in afourth generation (4G) Long Term Evolution (LTE). One or more BAWdevices in accordance with any suitable principles and advantagesdisclosed herein can be included in a filter having a passband thatincludes a 4G LTE operating band operating band and a 5G NR operatingband. Such a filter can be implemented in a dual connectivityapplication, such as an E-UTRAN New Radio—Dual Connectivity (ENDC)application.

BAW devices disclosed herein can provide high Q and/or high Q stabilityin the presence of manufacturing variations. Such features can beadvantageous in 5G NR applications. For example, Q stability for BAWdevices can be significant in meeting 5G performance specifications atthe filter level and/or at the system level.

FIG. 34 is a schematic diagram of one example of a communication network410. The communication network 410 includes a macro cell base station411, a small cell base station 413, and various examples of userequipment (UE), including a first mobile device 412 a, awireless-connected car 412 b, a laptop 412 c, a stationary wirelessdevice 412 d, a wireless-connected train 412 e, a second mobile device412 f, and a third mobile device 412 g. UEs are wireless communicationdevices. One or more of the macro cell base station 141, the small cellbase station 413, or UEs illustrated in FIG. 34 can implement one ormore of the acoustic wave filters in accordance with any suitableprinciples and advantages disclosed herein. For example, one or more ofthe UEs shown in FIG. 34 can include one or more acoustic wave filtersthat include any suitable number of BAW resonators with a multi-gradientraised frame structure.

Although specific examples of base stations and user equipment areillustrated in FIG. 34, a communication network can include basestations and user equipment of a wide variety of types and/or numbers.For instance, in the example shown, the communication network 410includes the macro cell base station 411 and the small cell base station413. The small cell base station 413 can operate with relatively lowerpower, shorter range, and/or with fewer concurrent users relative to themacro cell base station 411. The small cell base station 413 can also bereferred to as a femtocell, a picocell, or a microcell. Although thecommunication network 410 is illustrated as including two base stations,the communication network 410 can be implemented to include more orfewer base stations and/or base stations of other types.

Although various examples of user equipment are shown, the teachingsherein are applicable to a wide variety of user equipment, including,but not limited to, mobile phones, tablets, laptops, Internet of Things(IoT) devices, wearable electronics, customer premises equipment (CPE),wireless-connected vehicles, wireless relays, and/or a wide variety ofother communication devices. Furthermore, user equipment includes notonly currently available communication devices that operate in acellular network, but also subsequently developed communication devicesthat will be readily implementable with the inventive systems,processes, methods, and devices as described and claimed herein.

The illustrated communication network 410 of FIG. 34 supportscommunications using a variety of cellular technologies, including, forexample, 4G LTE and 5G NR. In certain implementations, the communicationnetwork 410 is further adapted to provide a wireless local area network(WLAN), such as WiFi. Although various examples of communicationtechnologies have been provided, the communication network 410 can beadapted to support a wide variety of communication technologies.

Various communication links of the communication network 410 have beendepicted in FIG. 34. The communication links can be duplexed in a widevariety of ways, including, for example, using frequency-divisionduplexing (FDD) and/or time-division duplexing (TDD). FDD is a type ofradio frequency communications that uses different frequencies fortransmitting and receiving signals. FDD can provide a number ofadvantages, such as high data rates and low latency. In contrast, TDD isa type of radio frequency communications that uses about the samefrequency for transmitting and receiving signals, and in which transmitand receive communications are switched in time. TDD can provide anumber of advantages, such as efficient use of spectrum and variableallocation of throughput between transmit and receive directions.

In certain implementations, user equipment can communicate with a basestation using one or more of 4G LTE, 5G NR, and WiFi technologies. Incertain implementations, enhanced license assisted access (eLAA) is usedto aggregate one or more licensed frequency carriers (for instance,licensed 4G LTE and/or 5G NR frequencies), with one or more unlicensedcarriers (for instance, unlicensed WiFi frequencies).

As shown in FIG. 34, the communication links include not onlycommunication links between UE and base stations, but also UE to UEcommunications and base station to base station communications. Forexample, the communication network 410 can be implemented to supportself-fronthaul and/or self-backhaul (for instance, as between mobiledevice 412 g and mobile device 412 f).

The communication links can operate over a wide variety of frequencies.In certain implementations, communications are supported using 5G NRtechnology over one or more frequency bands that are less than 6Gigahertz (GHz) and/or over one or more frequency bands that are greaterthan 6 GHz. According to certain implementations, the communicationlinks can serve Frequency Range 1 (FR1), Frequency Range 2 (FR2), or acombination thereof. An acoustic wave filter in accordance with anysuitable principles and advantages disclosed herein can filter a radiofrequency signal within FR1. In one embodiment, one or more of themobile devices support a HPUE power class specification.

In certain implementations, a base station and/or user equipmentcommunicates using beamforming. For example, beamforming can be used tofocus signal strength to overcome path losses, such as high lossassociated with communicating over high signal frequencies. In certainembodiments, user equipment, such as one or more mobile phones,communicate using beamforming on millimeter wave frequency bands in therange of 30 GHz to 300 GHz and/or upper centimeter wave frequencies inthe range of 6 GHz to 30 GHz, or more particularly, 24 GHz to 30 GHz.

Different users of the communication network 410 can share availablenetwork resources, such as available frequency spectrum, in a widevariety of ways. In one example, frequency division multiple access(FDMA) is used to divide a frequency band into multiple frequencycarriers. Additionally, one or more carriers are allocated to aparticular user. Examples of FDMA include, but are not limited to,single carrier FDMA (SC-FDMA) and orthogonal FDMA (OFDMA). OFDMA is amulticarrier technology that subdivides the available bandwidth intomultiple mutually orthogonal narrowband subcarriers, which can beseparately assigned to different users.

Other examples of shared access include, but are not limited to, timedivision multiple access (TDMA) in which a user is allocated particulartime slots for using a frequency resource, code division multiple access(CDMA) in which a frequency resource is shared amongst different usersby assigning each user a unique code, space-divisional multiple access(SDMA) in which beamforming is used to provide shared access by spatialdivision, and non-orthogonal multiple access (NOMA) in which the powerdomain is used for multiple access. For example, NOMA can be used toserve multiple users at the same frequency, time, and/or code, but withdifferent power levels.

Enhanced mobile broadband (eMBB) refers to technology for growing systemcapacity of LTE networks. For example, eMBB can refer to communicationswith a peak data rate of at least 10 Gbps and a minimum of 100 Mbps foreach user. Ultra-reliable low latency communications (uRLLC) refers totechnology for communication with very low latency, for instance, lessthan 3 milliseconds. uRLLC can be used for mission-criticalcommunications such as for autonomous driving and/or remote surgeryapplications. Massive machine-type communications (mMTC) refers to lowcost and low data rate communications associated with wirelessconnections to everyday objects, such as those associated with Internetof Things (IoT) applications.

The communication network 410 of FIG. 34 can be used to support a widevariety of advanced communication features, including, but not limitedto, eMBB, uRLLC, and/or mMTC.

Any of the embodiments described above can be implemented in associationwith mobile devices such as cellular handsets. The principles andadvantages of the embodiments can be used for any systems or apparatus,such as any uplink wireless communication device, that could benefitfrom any of the embodiments described herein. The teachings herein areapplicable to a variety of systems. Although this disclosure includessome example embodiments, the teachings described herein can be appliedto a variety of structures. Any of the principles and advantagesdiscussed herein can be implemented in association with RF circuitsconfigured to process signals in a frequency range from about 30 kHz to300 GHz, such as in a frequency range from about 450 MHz to 5 GHz, in afrequency range from about 450 MHz to 8.5 GHz or in a frequency rangefrom about 450 MHz to 10 GHz.

Aspects of this disclosure can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products such as packaged radio frequency modules, uplinkwireless communication devices, wireless communication infrastructure,electronic test equipment, etc. Examples of the electronic devices caninclude, but are not limited to, a mobile phone such as a smart phone, awearable computing device such as a smart watch or an ear piece, atelephone, a television, a computer monitor, a computer, a modem, ahand-held computer, a laptop computer, a tablet computer, a microwave, arefrigerator, a vehicular electronics system such as an automotiveelectronics system, a stereo system, a digital music player, a radio, acamera such as a digital camera, a portable memory chip, a washer, adryer, a washer/dryer, a copier, a facsimile machine, a scanner, amulti-functional peripheral device, a wrist watch, a clock, etc.Further, the electronic devices can include unfinished products.

Unless the context indicates otherwise, throughout the description andthe claims, the words “comprise,” “comprising,” “include,” “including”and the like are to generally be construed in an inclusive sense, asopposed to an exclusive or exhaustive sense; that is to say, in thesense of “including, but not limited to.” Conditional language usedherein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,”“for example,” “such as” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orstates. The word “coupled”, as generally used herein, refers to two ormore elements that may be either directly connected, or connected by wayof one or more intermediate elements. Likewise, the word “connected”, asgenerally used herein, refers to two or more elements that may be eitherdirectly connected, or connected by way of one or more intermediateelements. Additionally, the words “herein,” “above,” “below,” and wordsof similar import, when used in this application, shall refer to thisapplication as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel resonators described hereinmay be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the resonatorsdescribed herein may be made without departing from the spirit of thedisclosure. Any suitable combination of the elements and/or acts of thevarious embodiments described above can be combined to provide furtherembodiments. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the disclosure.

What is claimed is:
 1. A bulk acoustic wave device with a multi-gradientraised frame, the bulk acoustic wave device comprising: a firstelectrode; a second electrode; a piezoelectric layer positioned betweenthe first electrode and the second electrode; and a multi-gradientraised frame structure including a first raised frame layer and a secondraised frame layer, the second raised frame layer extending beyond thefirst raised frame layer, and the second raised frame layer beingtapered on opposing sides, and the bulk acoustic wave device beingconfigured to generate a bulk acoustic wave.
 2. The bulk acoustic wavedevice of claim 1 wherein the second raised frame layer extends beyondthe first raised frame layer on the opposing sides, and the opposingsides include a first side toward a main acoustically active region ofthe bulk acoustic wave device and a second side away from the mainacoustically active region.
 3. The bulk acoustic wave device of claim 1wherein the first raised frame layer has a lower acoustic impedance thanthe piezoelectric layer.
 4. The bulk acoustic wave device of claim 1wherein the first raised frame layer includes an oxide, and the secondraised frame layer includes a metal.
 5. The bulk acoustic wave device ofclaim 4 wherein the second raised frame layer incudes one or more ofruthenium, molybdenum, tungsten, platinum, or iridium.
 6. The bulkacoustic wave device of claim 1 wherein the first raised frame layerincludes a metal.
 7. The bulk acoustic wave device of claim 1 whereinthe first raised frame layer includes a polymer.
 8. The bulk acousticwave device of claim 1 wherein the multi-gradient raised frame structurehas a non-gradient portion between two gradient portions.
 9. The bulkacoustic wave device of claim 1 wherein the first raised frame layer ispositioned between the first electrode and the second electrode.
 10. Thebulk acoustic wave device of claim 1 wherein the second electrode ispositioned between the second raised frame layer and the first raisedframe layer.
 11. The bulk acoustic wave device of claim 10 wherein thefirst raised frame layer is positioned between the piezoelectric layerand the second electrode.
 12. The bulk acoustic wave device of claim 1wherein the second raised frame layer has a first taper angle on a firstside and a second taper angle on a second side, and the first and secondtaper angles are each greater than 5 degrees and less than 45 degrees.13. The bulk acoustic wave device of claim 1 wherein the second raisedframe layer is a convex structure relative to a surface of thepiezoelectric layer.
 14. The bulk acoustic wave device of claim 1wherein the multi-gradient raised frame structure surrounds a mainacoustically active region of the bulk acoustic wave device in planview.
 15. The bulk acoustic wave device of claim 1 wherein the bulkacoustic wave device is a film bulk acoustic resonator.
 16. An acousticwave filter comprising: a bulk acoustic wave device including a firstelectrode, a second electrode, a piezoelectric layer positioned betweenthe first electrode and the second electrode, and a multi-gradientraised frame structure including a first raised frame layer and a secondraised frame layer, the second raised frame layer extending beyond thefirst raised frame layer, and the second raised frame layer beingtapered on opposing sides; and at least one additional acoustic wavedevice, the bulk acoustic wave device and the at least one additionalacoustic wave device together arranged to filter a radio frequencysignal.
 17. The acoustic wave filter of claim 16 wherein the at leastone additional acoustic wave device includes a second bulk acoustic wavedevice that includes a second multi-gradient raised frame structure thatis tapered on opposing sides.
 18. A packaged radio frequency modulecomprising: an acoustic wave filter including a bulk acoustic wavedevice, the bulk acoustic wave device including a first electrode, asecond electrode, a piezoelectric layer positioned between the firstelectrode and the second electrode, and a multi-gradient raised framestructure including a first raised frame layer and a second raised framelayer, the second raised frame layer extending beyond the first raisedframe layer, and the second raised frame layer being tapered on opposingsides, the acoustic wave filter configured to filter a radio frequencysignal; a radio frequency circuit element; and a package structureenclosing the acoustic wave filter and the radio frequency circuitelement.
 19. The packaged radio frequency module of claim 18 wherein theradio frequency circuit element is a radio frequency switch.
 20. Thepackaged radio frequency module of claim 18 wherein the radio frequencycircuit element is a radio frequency amplifier.